Europe is home to many traditional and monumental buildings that have become landmarks in many European cities. These buildings are a tangible link to our past and allow us to better appreciate our cultural, architectural, and societal heritage. Nevertheless, they generally require significant use of energy and generate higher than average greenhouse gas emissions. Renovating historic buildings and bringing them up to date with current energy efficiency standards is therefore essential. However, the process is often impaired under the argument that said renovation could potentially damage their cultural and aesthetic heritage, says Dàlia Puig, junior science communicator, at the European Science Communication Institute.

Despite this, new innovative technologies are defying this statement. An example is the retrofitting of the Basilica di Santa Maria di Collemaggio in L’Aquila, Italy. Founded in 1228, this basilica is considered one of the greatest expressions of Abruzzo architecture and an example of best practices for the energy-efficient renovation of historic buildings. Due to damage caused by a regional earthquake in 2009, the basilica was closed to the public in 2013 and had to undergo a complete retrofit (from 2015 to 2017) before it could be once again opened four years later. The restoration was taken as a chance to marry renovation with innovation. As part of the retrofitting works, new geothermal heat pumps were installed, and radiant panels were placed on the inside of the basilica’s benches. This allowed the heat to be specifically directed to people instead of lost heating up the air. Ultimately, renovation works were able to increase the energy efficiency of the building while preserving its original cultural and architectural elements in such a seamless way that they earned a European heritage Conservation Award in 2020.

Decarbonising Europe’s building sector

Similarly, to the case of the Basilica di Santa Maria di Collemaggio, many novel retrofitting projects have been developed over recent years thanks to the new technologies arising. In fact, some examples can be found in the Historic Building Energy Retrofit Atlas, a platform coordinated by the Italian research centre EURAC Research.

Nevertheless, the issue of energy inefficiency extends far beyond historical buildings. In fact, it is deeply rooted within the foundation of our homes. According to the European Commission (EC), around half of the European residential buildings were built before the introduction of thermal standards (1970), which makes them highly inefficient. In fact, according to the EC if all existing residential buildings in the EU were renovated 44% of the energy used for residential space heating could be saved.

“However, one of the fundamental problems in the renovation market is that often the promised savings aren't delivered in practice,” explains James Thorogood, project coordinator and policy advisor at Eurocities. According to him, this is because there is a significant issue regarding the capability of the construction market, especially given the state of the existing housing stock. For example, since most of the existing residential buildings are over 50 years old, renovation projects usually encounter a lot of issues regarding asbestos. Furthermore, when retrofitting residential buildings there are many other elements to be considered, such as windows and doors. “Windows and doors are very expensive and can form a significant proportion of the cost of a retrofitting project. However, these elements may not actually play a key role in delivering the energy saving in the way loft insulation or cavity insulation would.,” says Thorogood.

To overcome the renovation gap, in 2020 the EC presented its Renovation Wave Strategy. With this initiative, the EC aims to double renovation rates in the next ten years and make sure renovations lead to higher energy and resource efficiency. Furthermore, as a part of this strategy, the EC has developed the Affordable Housing Initiative, focused on ensuring that social and affordable housing also benefits from the renovation wave.

Promoting socially inclusive renovations

Under the Affordable Housing Initiative, the EC has funded several projects that strive to renovate affordable housing according to an integrated approach that combines technological innovation, co-creation with residents, and the use of innovative business models. For example, the SHAPE-EU project, co-founded by Eurocities, aims to support public, social, and cooperative housing providers to deliver socially inclusive and affordable renovations across European districts. Sibling to SHAPE-EU is ProLight, a project that intends to use a smart neighbourhood approach to build energy communities, in which residents can be aware of their energy consumption and actively engage in the renovation process.

“Our project is unique because it is the first time, as far as we know, that such renovation actions are being designed in a comprehensive way and in accordance with the interest of providing a good quality of life to the residents of our neighbourhoods.”, states Johannes Zeininger, architect of the ProLight demonstration site in Vienna.

Situated in the Hernals district, the Viennese site is the most advanced of the six ProLight demonstration neighbourhoods. A geothermal heating system has been installed on-site, in combination with renewable solar-thermal energy generation. “We call our concept Geothermal 2.0. This is because we don’t use the traditional geothermal energy method, which is very slow and needs very wide distances between boreholes. In our case, the ground is used as an energy reservoir, not a source. It is like having an energy battery in the ground”, explains Zeininger. This unique approach captures solar energy during summer using photovoltaic panels and solar mats and can store the thermal energy in the ground. This stored energy can then be depleted during winter as needed. Furthermore, the system is modular, which means that whenever a new house in the quarter is renovated it can be added to the stand-alone network where it can exchange its energy with other households, leading to higher energy efficiency and a developed sense of community.

Initiatives such as ProLight and SHAPE-EU are paving the way towards the decarbonisation of Europe’s building sector, which currently represents 32% of European CO2 emissions, according to the European Climate Foudation. If successful, projects could demonstrate that there is an economically, energetically, and resource-efficient way to renovate affordable housing that ensures a better quality of life for vulnerable communities. Furthermore, they could provide blueprints for replication that can be implemented across Europe, meeting the specific needs of each neighbourhood.